Ordinance firing system for land vehicle

ABSTRACT

An ordnance system of the present invention may include or feature any one or more of: a control unit, one or more effectors (detonators, initiators, shaped charges and the like), and a two-, three- or four-wire communication bus between the control unit and the effectors; an addressable system in which all the effectors can be connected to the same communication bus and the control unit can issue coded signals on the bus addressed to a specific effector; inductive coupling between the effectors and the communication bus; and a multi-voltage level communication system in which communication signals are carried at a first voltage and arming signals are provided at a second, higher voltage. Other features may include two-way communication between effectors and the control unit and the de-centralization of firing control so that the control unit does not have exclusive control over whether the effectors function. As a result, the individual effectors possess decision-making ability and, for purposes of this invention, may be referred to as “intelligent” effectors. To participate in the decision-making process, effectors of this invention may be equipped with sensors or other diagnostic circuitry whose condition is checked for satisfactory output before functioning is permitted to occur.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. application Ser. No. 09/810,089,filed Mar. 16, 2001, which claims benefit of U.S. provisionalapplication No. 60/190,458, filed Mar. 17, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the initiation of explosive and pyrotechnicdevices in aerospace and aeronautical devices and automotive vehicles.

2. Related Art

Explosive and pyrotechnic devices such as explosive bolts, bolt cutters,separation fairings, actuators, engine igniters, etc., are used inaeronautical and aerospace applications to perform various functionssuch as the separation of one structure from another, the release of astructure from a stowed position to a deployed position, etc. They arealso used in the safety systems of land vehicles such as automobiles,for the deployment of air bags. Such devices are typically coupled toelectrically operated initiators which, in response to suitableelectrical signals, initiate the devices. The initiation signals areprovided by electronic control devices for controlling and coordinatingthe initiation of a plurality of initiators connected thereto. Thecombination of a control unit, a plurality of initiators and anelectrical communication system through which signals are sent from thecontroller to the initiators is referred to herein as an “ordnancefiring system”.

In the prior art of aeronautical and aerospace devices such as missiles,satellites, launch vehicles, etc., and of land vehicle safety systems,the initiators in the ordnance firing systems that control the variousexplosive or pyrotechnic effectors (hereinafter referred to collectivelyas “reactive effectors”) typically comprise a hot bridgewire initiatingelement and an initiating charge of explosive or pyrotechnic materialwhich is sensitive to the initiating element. In order to stimulate thehot bridgewire initiating element to release sufficient energy to ignitethe ignition charge, a large amount of electrical energy (relative towhat is generally required for most other functions on such devices) isrequired. For example, the firing of a hot bridgewire initiatortypically requires a draw of ten amps from a 28-volt source for a periodof about 0.1 second. Since there are often numerous effectors on a givendevice, the total energy requirement for initiation of the effectors farexceeds the energy requirement for operation of the circuitry thatcontrols the device. For this reason, prior art ordnance firing systemstypically include a dedicated high power energy source such as a thermalor chemical battery, for the purpose of providing sufficient energy tofire the hot bridgewires. The need in aerospace and aeronautical devicesto provide such batteries, which are large and heavy, has been viewed asan unavoidable but significant burden. The batteries occupy space whichcould go to other, more useful components of the device or to increasedpayload capacity and, for airborne devices, they also increase the fuelconsumption of the device at all times during flight.

Another feature of prior art ordnance firing systems is that all controlfunctions affecting whether the effectors will function reside in acontrol system, from which command signals are forwarded to theeffectors on dedicated wires.

U.S. Pat. No. 4,708,060 to Bickes, Jr. et al, dated Nov. 24, 1987 andentitled “Semiconductor Bridge (SCB) Igniter”, discloses SCB igniterelements, which are described as comprising an electrical semiconductormaterial disposed on a non-conductive substrate. The semiconductormaterial may be, e.g., a layer of n-type silicon that has been dopedwith phosphorus. As indicated in this Patent, other semiconductormaterials and dopants can be used with similar effect. The resistivityof the doped material varies with the dopant level, as iswell-understood in the art. Typically, the semiconductor material isdisposed on the non-conductive substrate by a chemical vapor depositionprocess by which the thickness of the material can be preciselycontrolled. The surface of the non-conductive substrate is usuallymasked during the deposition process so that the layer of semiconductormaterial is rendered in an hourglass shape, i.e., it forms tworelatively large pads joined together by a small bridge. Two pads ofconductive material are then disposed upon the large pads of thesemiconductor material and are separated by the bridge of semiconductormaterial between them. The resistivity of the semiconductor material andthe dimensions of the semiconductor bridge between the conductive padsdetermines the effective resistance that the semiconductor bridgeprovides between the conductive pads. The Patent teaches a preferencefor SCBs of low resistance, e.g., no larger than 10 ohms, for safetyreasons, i.e., in case the SCB is used with an electrostatic sensitiveignition charge (see column 7, lines 44-50) and for a reduction inresistivity with an increase in SCB size (see column 7, lines 53-55).The firing data provided pertain to high amperage (e.g., 10 amps andhigher), short duration electrical initiation signals of less than 100microseconds duration (see column 5, line 62 through column 6, line 3).The comparative data of Table 2 are difficult to interpret because SCB1and SCB2 differ not only in resistance but also in thickness (2micrometers vs. 4 micrometers).

U.S. Pat. No. 5,831,203 to Ewick, dated Nov. 3, 1998, discloses a highimpedance semiconductor bridge detonator which illustrates, inter alia,that a SCB initiator element may be manufactured on a non-electricallyconducting substrate using photolithographic masking, chemical vapordeposition, etc.

U.S. Pat. No. 4,976,200 to Benson et al, dated Dec. 11, 1990, disclosestitanium bridge igniters.

U.S. Pat. No. 5,085,146 to Baginski, dated Feb. 4, 1992, discloses aplanar, multi-layer low-energy initiation element.

SUMMARY OF THE INVENTION

This invention pertains to an aerospace device comprising a plurality ofreactive effectors and, in particular, to the improvement comprising aplurality of initiators comprising planar, low-energy initiationelements operatively associated with the effectors for initiating thesame.

According to one aspect of the invention, the device may comprise alow-energy power source connected to the initiators to provide power forarming the initiators.

According to another aspect of the invention, the device may furthercomprise a firing control system circuitry connected to the initiatorsfor controlling the firing of the plurality of initiators, and alow-energy power source for arming the initiators. Optionally, there maybe a common communication bus connecting the initiators to the controlcircuitry.

In particular embodiments, the device may comprise a missile or launchvehicle. Any such device may comprise effectors selected from the groupconsisting of exploding bolts, bolt cutters, motor igniters, releasefairings and destruct charges.

This invention also pertains to an aerospace device comprising aplurality of reactive effectors and, in particular, to the improvementcomprising a plurality of initiators associated with the effectors, afiring control system in communication with the initiators, and at leastone sensor, on the device, for sensing a condition precedent to armingor firing at least one initiator, wherein at least one initiator is incommunication with the sensor and that is responsive to the sensor andto the firing circuitry for initiating its associated effector uponreceipt of proper signals from both the firing circuitry and the sensor.

Optionally, the device may comprise a common bus through which theinitiators are linked to the firing circuitry. The sensor may beconnected to the bus or to the initiator responsive to it.

At least one initiator may be programmed to self-arm or initiate basedon a signal received from the sensor.

This invention also provides a method for firing an initiator for areactive effector in an aerospace device or land vehicle comprising atleast one sensor for a condition precedent to firing the initiator. Themethod comprises taking a time-phased reading of the sensor andcomparing the reading to a predetermined temporal profile, and firingthe initiator when the reading correlates to the predetermined profile.

Another aspect of this invention relates to a land vehicle comprising aplurality of reactive effectors and, in particular, to the improvementcomprising initiators comprising planar, low-energy initiation elementsfor initiating the effectors.

According to one aspect of the invention, the vehicle may comprise alow-energy power source connected to the initiators to provide power forarming the initiators.

Optionally, the vehicle may further comprise a firing control systemcircuitry connected to the initiators for controlling the firing of theplurality of initiators for the effectors, and a low-energy power sourcefor arming the initiators. There may be a common communication busconnecting the initiators to the control circuitry. Optionally, theeffectors may comprise air bag inflators.

This invention also pertains to a land vehicle comprising a plurality ofreactive effectors and, in particular, to the improvement comprising aplurality of initiators associated with the effectors, a firing controlsystem in communication with the initiators, and at least one sensor, onthe device, for sensing a condition precedent to arming or firing atleast one initiator, wherein at least one initiator is in communicationwith the sensor and that is responsive to the sensor and to the firingcircuitry for initiating its associated effector upon receipt of propersignals from both the firing circuitry and the sensor.

In various embodiments, there may be a common bus through which theinitiators are linked to the firing circuitry; the sensor may beconnected to the bus; the sensor may be connected to the initiatorresponsive to it; and/or at least one initiator may be programmed toself-arm or initiate based on a signal received from the sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic block diagram of an integrated ordnance firingsystem for a missile in accordance with one embodiment of the presentinvention;

FIG. 1B is a schematic cross-sectional view of a SCB initiator for usein an aero-space ordnance firing system according to a particularembodiment of the present invention;

FIG. 1C is a block diagram of an embodiment of an ordnance firingcontrol system according to this invention, which draws power from othercircuitry;

FIG. 2 is a partial schematic block diagram of an initiator inconnection with a particular embodiment of the invention;

FIG. 3 is a graph illustrating the time-phased arming of an initiator inaccordance with another embodiment of the invention;

FIG. 4 is a schematic block diagram of an initiator in accordance withyet another embodiment of the invention;

FIG. 5 is a schematic block diagram of an initiator in accordance withyet another embodiment of the invention; and

FIG. 6 is a schematic block diagram of a prior art ordnance firingsystem for a missile.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

The present invention relates to an ordnance firing system for anaerospace device or a land vehicle comprising a plurality of reactiveeffectors. In one embodiment, the system comprises firing control systemcircuitry for controlling the firing of a plurality of initiators, aplurality of initiators comprising planar low-energy initiation elementsconnected to the firing control system circuitry, a low-energy powersource for arming the initiators and a low-energy power source forpowering the control circuitry.

In another embodiment, the invention relates to an ordnance firingsystem for an aerospace device or a land vehicle comprising a pluralityof reactive effectors and a firing control system for controlling thefiring of a plurality of initiators. In this embodiment, the firingcontrol system comprises a low-energy power source and an input port forreceiving low-energy power for arming the initiators and for poweringthe firing control system and for receiving firing control signals.There is also a plurality of initiators comprising planar, low-energyinitiation elements connected to the firing control circuitry.

Optionally, a system according to this invention may comprise a commoncommunication bus connecting the initiators to the control circuitry.

An ordnance firing system in accordance with the present invention maybe utilized on numerous kinds of aeronautical and aerospace devices suchas tactical missiles, cruise missiles, surface-to-air missiles, launchvehicles, satellites, etc. (as used herein, the term “aerospace devices”is meant to include aeronautical devices). In such devices, the ordnancesystem is used to initiate the function of various explosive orpyrotechnic effectors such as exploding bolts, bolt cutters, frangiblejoints, actuators, penetration charges, fragmentation charges, gasgenerators, inflators, motor igniters, through bulkhead initiators,explosive transfer lines, separation devices, destruct charges,pyrotechnically actuated valves, etc., referred to collectively hereinas “reactive effectors” to include both explosive and pyrotechniceffectors. The ordnance firing system of this invention can also be usedin land vehicles that utilize reactive effectors, e.g., in air bagdeployment systems.

One feature of the present invention is that instead of hot bridgewireinitiators, an ordnance firing system in accordance with this inventionemploys initiators that comprise planar, low-power initiation elements,e.g., semiconductor bridge (“SCB”) initiators, tungsten bridgeinitiators as described, e.g., in U.S. Pat. No. 4,976,200, which ishereby incorporated herein by reference, or the type of planar,low-energy initiation element disclosed in U.S. Pat. No. 5,085,146,which is hereby incorporated herein by reference. As a result, the powerrequirement for arming and firing the initiators, and therefore forcausing the effectors to function, is enormously reduced relative toprior art ordnance systems. This is because a planar, low-energyinitiator typically requires only one-tenth the amount of energy tofunction than would be required by a hot bridgewire of comparablereliability and safety. Other prior art initiation elements, e.g.,exploding bridgewires, exploding foil initiators, etc., require evenmore energy than hot bridgewires. Accordingly, where prior art ordnancefiring systems require hundreds of watts of power or more, acorresponding system based on planar, low-energy initiation elements inaccordance with this invention requires only tens of watts or less. Thismeans that an integrated ordnance system according to this invention maybe configured differently from prior art ordnance firing systems. Onedifference is that an ordnance firing system according to this inventiondoes not require a large power source for firing the initiators. Where adedicated power source is provided, a much smaller power source can beused or, in some embodiments, the need for a power source dedicatedsolely to firing the initiators may be eliminated completely.Alternatively, the initiators may optionally contain storage means, suchas a firing capacitor, for storing sufficient energy to fire theinitiation element. Due to the small energy requirement of theinitiation element, the storage means is small enough to incorporateinto the initiator. Typically, the firing capacitor need only provideabout 5 millijoules to provide twice the energy requirements of theplanar initiation element, which typically consumes less than 3millijoules upon firing. In addition, it is possible to charge thefiring capacitor without requiring a large amount of energy, so theinitiator control circuitry can have a relatively high impedance, asdiscussed further below. In fact, the storage capacitor may be chargedfrom power received from the power source provided to enable the controlcircuitry to function. As a result, an enormous savings is seen withrespect to the cost, weight, physical volume and fuel consumption of theordnance firing system for the aerospace device.

If a hot bridgewire or other device known in the prior art for use inaerospace or land vehicle ordnance initiation systems (explodingbridgewire, exploding foil, etc.) were designed to function at thelow-energy level of the planar initiators used in accordance with thisinvention, it would not offer the combined safety and reliabilityrequired in the aerospace and automotive safety industries. Theapplicants have found, however, that initiators that meet generallyaccepted safety specifications and which function reliably in aerospacedevices and land vehicles, and which require significantly less energyupon firing than prior art devices can be achieved by the use of planar,low-energy initiation elements as described herein. One crucialdifference is that planar initiation elements are typically formed onheat-dispersing material such as a silicon or sapphire substrate whichacts as a heat sink for the initiation element. The initiation elementcan therefore tolerate a significant degree of stray energy within theno-fire limit, whereas a bridgewire or other prior art element typicallycannot dissipate heat as quickly and therefore is more vulnerable tostray currents. A planar initiation element can therefore maintain asatisfactory no-fire characteristic (e.g., 1 ampere, 1 watt) even whenit is designed to fire with low energy, e.g., less than 3 millijoules.

In addition to a reduction in the power requirement and the potentialelimination of the need for a dedicated power source, the presentinvention allows for significant reduction in size of the initiator,even though a storage means (firing capacitor) for firing the initiatoris disposed within the initiator housing. Part of the reason for thissize reduction is that the low-energy initiation element does notrequire associated circuitry with the power handling capacity of priorart initiators. Thus, circuit elements such as the firing switch and thefiring control circuitry in the initiator can be assembled from circuitelements that are much smaller than those required in prior artinitiators.

In addition, the present invention provides an ordnance firing systemwith initiators comprising initiator control circuits having numerousfeatures described below, any one or more of which may be present aloneor in combination with any other features disclosed herein.

This invention provides an ordnance firing system characterized by novelconfigurations of initiators, a firing control system and acommunication structure. The novel configurations pertain to thestructure of the initiators to which the control system is connected,the mode for connecting the initiators to the firing control system andone or more modes of operation of the ordnance firing system, i.e.,modes of operation by which the firing control system and initiatorscooperate to operate the effectors with which the initiators areassociated. The communication structure of an ordnance firing system ofthe present invention may include or feature any one or more of: a two-,three- or four-wire communication bus between the control unit and theinitiators; an addressable initiator system in which all the initiatorscan be connected to the same communication bus and the firing controlsystem unit can issue coded signals on the bus addressed to a specificinitiator; the use of inductive coupling between the initiators and thecommunication bus; the use of a multi-voltage level communication systemin which communication signals are carried at a first voltage and armingsignals are provided at a second, higher voltage. Other features mayinclude the use of two-way communication between initiators and thefiring control system unit and the de-centralization of firing controllogic so that the firing control system does not have exclusive controlover whether the initiators function. An initiator for use in aerospacedevices or land vehicles according to this invention may thereforeinclude initiator control circuitry of its own and as a result, theindividual initiators are seen to possess decision-making ability and,for purposes of this invention, are therefore referred to as“intelligent” initiators. To participate in the decision-making process,initiators of this invention may be equipped with sensors or otherdiagnostic circuitry whose condition is checked for satisfactory outputbefore functioning is permitted to occur. Other safety features,described herein, may be present as well.

A prior art missile equipped with guidance circuitry and ordnancecontrol circuitry in accordance with the prior art is depicted in FIG.6. Missile 110 is shown schematically as comprising guidance and controlcircuitry 117 which includes its own power source 1 19, a low-powerbattery of size, weight and energy sufficient only for poweringcircuitry 117. Typically, an aerospace control circuit for an aerospacedevice comprises an integrated circuit, e.g., a microcomputer or anASIC, which requires small amounts of power and for which a low-energypower source 119 capable of providing not more than 50 watts istypically provided. In addition, missile 110 comprises ordnancecontroller circuitry 112 and a plurality of initiators 116, 118, 120,122 which are associated with various reactive effectors. Circuitry 112connects to the initiators via separate channel lines, typically witheach initiator on its own line. As indicated above, the initiators arecoupled to effectors which may constitute a variety of different kindsof devices, e.g., separation devices such as exploding bolts, boltcutters, explosive nuts, inflators, actuators, and the like, forcarrying out various functions of the missile in flight, e.g., therelease of stages or strap-on accessories, the deployment of aerodynamicfins, the initiation of an explosive munition, cutters for the releaseof a panel and an inflator for dispelling a pay-load, e.g., bomblets,through the opening provided by the cut panel, etc. Prior art initiators116, 118, etc., function by the use of a hot bridgewire or other priorart initiating element which consumes a large amount of electricalpower. For this reason, missile I 10 carries a high-power energy source115, which may be a chemical or thermal battery or the like capable ofproviding the hundreds of watts needed by each of the initiators. Theseparate power supply is needed because the power requirements forarming and firing the prior art initiators exceeds what can be providedby a power supply normally sufficient for powering guidance and controlcircuitry 117. It will be appreciated that missile 110 of FIG. 6 isrepresentative of various other kinds of aerospace or aeronauticaldevices which may employ an integrated ordnance system in accordancewith this invention.

FIG. 1A provides a schematic illustration of a missile 10 equipped withan ordnance firing system in accordance with the present invention. Theordnance firing system comprises a firing control system 12, acommunication bus 14, and a plurality of initiators 16, 18, 20, 22 forreactive effectors on the device. The initiators are connected to thebus 14 and a remote sensor 24 is also connected to bus 14.

By virtue of the present invention, missile 10 exhibits severalsignificant advantages over prior art missile 110 (FIG. 6). First,initiators 16, 18, 20 and 22 comprise planar, low-energy initiators asdisclosed herein, e.g., SCB initiators, tungsten bridge initiators, etc.These initiators are designed to function reliably and safely and withmuch less power than prior art initiators. As a result, the ordnancefiring system does not need a high-energy power source of the power,size or weight scale of high-energy power source 115 (FIG. 6). Instead,the circuitry which controls the functioning of the initiators ispowered by a low-energy power source 17 (FIG. 1A) which is sufficientfor the arming and firing of the initiators. Low-energy power source 17is the kind of power source normally associated with integrated controlcircuitry and, optionally, the same power source may be used to providepower for the guidance circuitry as well as for the ordnance firingcircuitry. For this reason, in one embodiment of this invention, theordnance firing system need not have its own power supply. Instead, itmay be configured to include a power input junction (e.g., a pin-typejunction) for connection to the power source for the other circuitrywith which it will be used. Such an embodiment of this inventiontherefore simply comprises initiators comprising planar, low-energyinitiator elements, the firing control system circuitry, thecommunication link between the initiators and the firing control systemcircuitry, and an input port for receiving power from the low-energypower source associated with the remainder of the circuitry on theaerospace device. The small energy requirements for a planar, low-energyinitiation element make possible the use of an energy storage device,i.e., firing capacitor, that may be connected to or formed as part ofthe integrated circuit comprising the firing circuitry of the initiator.Due to the low energy consumption of a planar, low-energy initiationelement, upon firing, the firing capacitor may be charged to its ready(“armed”) state by power provided by the low-energy power source.

Reduction in power consumption may also be realized by using highimpedance initiator firing circuitry. Therefore, in accordance with thepresent invention, the circuitry within initiators 16, 18, etc., mayprovide an input impedance of 1,000 ohms or more, e.g., 1,000 to 10,000ohms. Providing such an unusually high input impedance also providesprotection against accidental initiation resulting from stray signals onbus 14. Optionally, the high input impedance can be attained byisolating the initiator circuitry from the communication bus by the useof resistors.

As indicated above, missile 10 is merely representative of one type ofaerospace device on which an ordnance firing system in accordance withthe present invention may be employed. Other such devices include launchvehicles, which require many of the functions required in missiles. Inaddition, launch vehicles often require additional functions for whichthe ordnance firing system of this invention may be employed. Forexample, a launch rocket may have a requirement pertaining to stageseparation, for which it may be necessary to initiate a plurality ofexploding cutters or fasteners such as exploding bolts, or to initiateone or more frangible joints of the kind described in U.S. Pat. No.6,125,762 to Fritz et al, dated Oct. 3, 2000, the disclosure of which ishereby incorporated herein by reference as background material. Otherfunctions may pertain to the release of structural elements such ascovers, the deployment of sub-munitions from a missile and to ignitingrocket motors. An ordnance firing system of this invention may also beused on satellites, which employ ordnance systems to control reactiveeffectors for the deployment of structures such as antennae and solarpanels. The advantage provided by this invention, i.e., use of alow-energy power source, is especially important in a satellite prior tothe deployment of the solar panels. To that point, the satellite mustfunction solely on energy provided from batteries stored thereon. Thereduction of weight resulting from the use of the SCB initiators inaccordance with the present invention and the use of a low-energy powersource which is significantly smaller and lighter than those which havebeen used in the prior art reduces the weight of the satellite andtherefore the fuel requirements of all stages of the rocket used toplace the satellite in orbit. Conversely, for a given rocketconfiguration, the use of the present invention permits, without addedcost, the deployment of a satellite with more hardware than waspreviously possible using prior art ordnance firing systems.

Another example of an aerospace device comprising reactive effectors forwhich the ordnance firing system of the present invention may beemployed is shown in U.S. Pat. No. 5,884,866 to Steinmeyer et al, datedMar. 23, 1999, which discloses a satellite dispenser for releasing aplurality of satellites into orbit from a launch vehicle. Similarly, theordnance firing system of this invention may be employed to initiate theeffectors shown in the following patents: U.S. Pat. No. 6,135,391 to VanWoerkom, dated Oct. 24, 2000, which discloses explosively actuated pinassembly effectors for a retention system for a detachable spacecraftcapsule; U.S. Pat. No. 6,016,999 to Simpson et al, dated Jan. 25, 2000,which discloses explosive bolt effectors for spacecraft platforms whichare released from a pre-deployment position; U.S. Pat. No. 5,823,469 toArkhangelsky et al, dated Oct. 20, 1998, which discloses explosive boltand pyro-push rod effectors for a missile launching and orientationsystem in which the missile comprises an annular body that can beejected during flight; and U.S. Pat. No. 5,529,264 to Bedegrew et al,dated Jun. 25, 1996, which discloses explosive bolt effectors for alaunch missile system. All of the foregoing patents are incorporatedherein by reference as background information.

The assembly of an initiator comprising a planar, low-energy initiationelement for use with effectors on an aerospace device or land vehiclewill now be described. A SCB is formed as is known in the prior art, toprovide a SCB initiation element on a non-conductive substrate for usein initiator 250 (FIG. 1B). Initiator 250 comprises an output housing252, a body portion comprising sleeve 254 and an input portioncomprising input connector 256. As indicated above, output housing 252is configured to conform to a standard interface commonly used foreffectors in aerospace devices, e.g., it may comprise a fitting inaccordance with a specification known in the aerospace industry asAS4395 (0.375-24 UNJF). As shown in FIG. 1B, such a housing comprises ahex nut portion 252 d and a threaded head portion 252 a for coupling toa threaded effector. Head portion 252 a contains a glass or ceramicinsulator on which a SCB 234 is mounted. The SCB 234 is disposed in arecess in which a reactive output charge 252 b is disposed. The outputcharge is maintained in the recess by a cushion material and arupturable disc 252 c which is welded to housing 252.

The output charge 252 b may comprise any suitable reactive materialwhich, upon functioning of the SCB initiation element, will react,displace or burst rupture disc 252 c and provide the output necessary toinitiate the associated effector. In one particular embodiment forproducing a pyrotechnic output, output charge 252 b may comprise azirconium/potassium perchlorate (ZPP) pyrotechnic mixture. It will beunderstood that other pyrotechnic materials could be used with, orinstead of, ZPP, and that an explosive material could be used if anexplosive output is desired. The term “reactive material” as used hereinencompasses both pyrotechnic and explosive materials. Output housing 252also includes a base portion 252 e which is welded to sleeve 254.

Within sleeve 254 is disposed initiator firing circuitry 254 a, whichpreferably comprises integrated circuitry. Initiator firing circuitry254 a may include communication circuitry and, optionally, a storagecapacitor for obtaining and storing energy for firing the SCB. Initiatorfiring circuitry 254 a communicates with the SCB initiation element viaoutput lines 254 b, and with the ordnance system firing controlcircuitry (not shown) by means of four wires connected to four pins,only two of which are shown, pins 256 a and 256 b, which are secured toinitiator 250 via input connector 256. Pins 256 a and 256 b and theother electrical conductor pins may be mounted in a glass plug in inputconnector 256. Input connector 256 is welded to sleeve 254 at the endopposite from output housing 252. Input connector 256 is preferablyconfigured as a standard connector, e.g., it may comprise a connector inaccordance with a specification known in the aerospace industry by thedesignation MIL-C-26482. Typically, output housing 252, sleeve 254 andinput connector 256 will all be formed from 304L stainless steel and theresulting initiator will be hermetically sealed to protect thecomponents therein.

In various embodiments, input connector 256 may be adapted to include asmany input pins (2, 3, 4, etc.) as is required by initiator firingcircuitry 254 a and the ordnance system firing control system (notshown). Likewise, it will be recognized by one of ordinary skill in theart that initiator 250 may comprise any other suitable coupling means inplace of, or in addition to, hex nut portion 252 d of the AS4395 fittingin order to secure initiator 250 to its associated effector. Suchcoupling means may include, for example, the features of a bayonet-stylemount, a latch-style mount, etc.

Referring again to FIG. 1A, another feature of the ordnance firingsystem of this invention is the use of a multi-line party bus forestablishing communication between the firing control system circuitryand the various initiators. This feature provides advantagesirrespective of whether an initiation system employs planar, low-energyinitiators and a low-energy power source. According to this feature,initiators 16, 18, 20 and 22 each contain communication circuitry forreceiving and evaluating signals received via communication bus 14 fromfiring control system 12 or, optionally, at least one remote sensor 24.Since all of the initiators are connected to the same communication bus14, they all receive each of the signals issued by firing control system12. However, in accordance with the present invention, initiators 16,18, etc., contain initiator firing circuits that are programmed torecognize an address portion of signals received on communication bus14. The initiator firing circuit is programmed only to respond to thosesignals that contain an address code identified with that initiator. Theaddress code may constitute a specific address unique in the system tothat initiator; it may be a “shared” address also recognized by someother initiators in the system but not all of them, or it may be a“universal” address which all initiators connected to bus 14 recognize.Firing control system 12 and remote sensor 24 are configured to emitsignals that contain the appropriate address codes so that the signalswill be recognized and acted upon by the appropriate initiators.

As a result of the use of coded signals, initiators 16, 18, etc., may beconnected to shared wires in communication bus 14 and bus 14 maytherefore comprise merely two or three communication wires. A four-wirebus might be used as well, to provide separate wires for arming power,operation power, communication and ground. Similarly, initiators 16, 18,etc., may optionally be configured to generate and emit initiatorsignals onto communication bus 14. Firing control system 12 may bedesigned to receive and interpret initiator signals received via bus 14.The signal emitted by an initiator may contain an identifier code thatis unique to the issuing initiator so that the firing control system candistinguish among signals from the various initiators. Accordingly, onefeature of the present invention is that firing control system 12 andinitiators 16, 18, etc., are configured for two-way communication alongbus 14. This feature of the invention allows for an ordnance firingsystem in which initiators can provide feedback to the control unitalong the bus. The ordnance firing system can be configured so that,prior to a firing sequence, the firing control system unit issues aquery signal to one or more initiators and the initiators respond toindicate their readiness to function.

One feature of an ordnance firing system according to this invention isthat the initiators may communicate with the firing control system toindicate their readiness to function before actually being armed. Thisgreatly enhances the safety with which such a query can be carried out.

Optionally, sensors connected to the bus may respond to query signals onbus 14 with sensor feedback signals. The sensor feedback signals mayoptionally report the result of a self-test in which the initiatorand/or sensor indicates the condition of its internal circuitry and/orits readiness to function. Likewise, remote sensor 24 may be equipped toissue a signal addressed to firing control system 12 that reflects acondition that bears on whether one or more of the initiators in thesystem should function. The content of the sensor signal from remotesensor 24 may be used to determine what other signals should be emittedby firing control system 12. Internal or external sensors for use in orwith any one of initiators 16, 18, etc., to measure any of a variety ofparameters may include an acceleration sensor, to sense up to 20 gacceleration or greater, and/or an atmospheric pressure sensor toindicate changes in atmospheric pressure or a rate of atmosphericpressure change. Other factors that might be reported by sensors couldinclude humidity or moisture and electromagnetic radiation.

Another advantage associated with the use of a communication bus asshown in FIG. 1A and the use of addressable initiators is that such asystem can easily be modified to accommodate any desired number ofinitiators. Prior art ordnance firing systems as represented in FIG. 6require individual wires for each initiator and their firing controlsystems have limited capacity with regard to the number of initiatorsthey can service. To utilize such a system in an aerospace devicerequiring more than the fixed maximum number of initiators, it isnecessary to install a second firing control unit for the additionalinitiators. In contrast, by employing a bus architecture, as manyinitiators as may be desired can be spliced into the bus. The associatedfiring control system is programmable and is easily adapted by one ofordinary skill in the art to control as many initiators as may bedesired to include on the bus.

Another feature of the present invention is that firing control system12 and initiators 16, 18, etc., may be configured so that differenttypes of signals are conveyed at different power levels, e.g., differentvoltage levels along bus 14. For example, communication signals, e.g.,signals from firing control system 12 intended only as a query to theinitiators for readiness, response signals from the initiators to firingcontrol system 12 indicating their readiness to be armed, and fireinitiation signals from firing control system 12 to the initiators mayoccur at a low power level, preferably lower than the no-fire thresholdof the initiators. In this way, test and programming signals that arenot intended themselves to arm and/or initiate the initiators arecarried out at a level that is insufficient to arm and/or initiate theinitiators even if the communication signals are somehow misinterpreted.Such communication signals may be carried on bus 14 at, e.g., about 7volts. When the system is ready for arming, the energy for arming theinitiators may be provided at a higher level than the communicationsignal level, e.g., at 28 volts. Optionally, the arm signal andcommunication signal can travel on separate communication wires in bus14. Bus 14 may comprise three wires, a power or arming wire, acommunication wire and a ground wire, or four wires to permit separationof the firing system power supply from the arming power wire. The use ofbus 14 obviates the need for direct, exclusive point-to-point hardwireconnections between the firing control system and each initiator.

Another feature of the present invention provides that initiators 16,18, etc., need not be hard-wired to bus 14. Instead, they may beconnected to bus 14 via magnetic or inductive couplings. Such couplingsprovide an advantage over hard-wire connections in that the magnetic orinductive coupling inherently acts as a buffer to prevent certain kindsof unwanted signals from flowing between the initiators and the bus. Inaddition, inductive coupling will permit reliable signal transfer in avariety of adverse conditions, e.g., in environments that may be dry,humid, wet, dirty, etc., and through a variety of media: vacuum, gas,liquids, solids, etc. Initiators designed for inductive coupling to bus14 can be designed to be especially resistant to malfunctions induced byelectrostatic discharge and ambient radio frequency signals when theyare not connected to the bus. An inductive coupling will also allow bothcommunication signals and power signals to be multiplexed on the samesignal medium. Optionally, the inductive coupling may be integrated intothe initiator housing.

As indicated above, one novel feature of the present invention is thatthe control over the firing event may reside more in initiators 16, 18,etc., than in the prior art. In a system according to the prior art, afiring control system 112 (FIG. 6) issues signals, e.g., a high-powerpulse, forcing the initiators to initiate the effectors, and theinitiators were not equipped to override the firing signal received fromthe control unit. Stated differently, with prior art initiators, asignal from the firing control system unit was sufficient to initiatefiring. In contrast, one aspect of the present invention provides“intelligent” initiators. Intelligent initiators possess initiatorcontrol circuitry having some ability to override a signal from thefiring control system indicating readiness to fire, thus de-centralizingthe firing decision from the firing control system. The firing signalfrom the firing control system then becomes one input or factor takeninto account by the initiator in deciding whether to fire. Other signalsbearing on the decision to fire may be derived from sensors to which theinitiator is responsive.

Where the ordnance firing system comprises one or more sensors, eachsensor may measure a condition which is a condition precedent to firing,i.e., some or all of the initiators in the ordnance firing system may berequired to delay firing until the sensor indicates that the conditionis obtained. For example, in the case of a missile, the sensor mayindicate distance from the plane from which the missile is fired and thecondition precedent may be a minimum required distance from the plane.Optionally, the initiator control circuitry and one or more initiatorsmay be programmed to postpone function until such a signal is receivedfrom the sensor. Therefore, the firing control circuitry of theintegrated ordnance system may provide only part of the instructions andimpetus required by the initiator to fire. For example, the firingcontrol circuitry may provide a signal indicating readiness to arm theinitiator and may provide a low-energy source for arming the initiator,but the initiator may then wait for input from the sensor beforefunctioning. This allows the system to respond to environmentalconditions that may vary after the firing control system has determinedthat conditions for firing are imminent. Such sensors may include theremote sensor 24 connected to bus 14. In other embodiments of theinvention, however, the sensor may be associated exclusively with theinitiator making the firing “decision”. For example, there is anexternal sensor 18 a associated with and directly connected to initiator18. Either or both of sensor 18 a and sensor 24 may sense, for example,any one or more environmental variables pertinent to the function of theinitiator or the ordnance system as a whole.

In various applications, external factors describing the motion of theinitiator or a device on which the initiator is mounted (e.g., a mortarshell) may be required to determine the proper conditions for firing.Sensors that indicate acceleration, roll rate, pitch, yaw, velocity,distance, altitude, attitude, temperature, hydraulic or atmosphericpressure, etc., may provide information that is significant to theproper functioning of the initiator 18. Initiator 18 may then compriseinitiator control circuitry that will, upon receipt of a firing signalfrom firing control system 12, receive and evaluate the output of sensor18 a and may then function only if it determines that sensor 18 aindicates favorable conditions. Similarly, initiator 22 is responsivenot only to signals from firing control system 12 but also to aninternal sensor 22 a which may sense conditions inside the initiatorshell. Such internal conditions may include the condition of the firingcircuitry of initiator 22, the condition of the output charge ofinitiator 22, etc. Other relevant internal conditions that might bereported by sensor 22 a include temperature, voltages, frequencies,current draw, initiation element continuity, etc. If a firing signal isreceived from firing control system 12 but the requisite signal is notreceived from the sensor 22 a, initiator 22 may optionally be programmedto postpone firing despite the firing signal from firing control system12. Sensor 22 a may thus provide a built-in test function formanufacturing quality as well as field reliability.

According to another aspect of the present invention, the decision toarm and/or initiate one or more initiators may be based on a time-phasedsequence of one or more sensor signals. In other words, the ordnancefiring system (i.e., the firing control system and/or one or moreintelligent initiators) may respond to a temporal characteristic orprofile of a sensor signal and thus to a temporal characteristic of theinternal or external condition associated with that sensor, rather thanto a single, instantaneous and possibly artificial or accidental valueof the signal or of the condition. For example, rather than makinginitiation dependent upon the receipt of a sensor signal that indicatesattainment of acceleration of 30 g or more (either as the sole conditionof initiation or as one of a combination of conditions), the system maybe programmed to respond to a signal having a predetermined temporalprofile which indicates that acceleration of 30 g or more is attainedand is followed by at least 3 seconds of acceleration of at least 3 g.As another example, initiation may depend upon receiving signals thatindicate that a pressure altitude of less than 500 feet is attainedafter a pressure altitude of at least 3000 feet is registered for atleast 10 minutes. Such temporal analyses of sensor signals permitgreater specificity in defining the conditions under which initiation isdesired than decision processes that respond merely to the instantaneousmagnitude of a sensor signal without regard to its temporal profile. Forexample, the temporal acceleration analysis described above permits thesystem to distinguish between the air-borne deployment of a munition andthe inadvertent dropping of the munition from a loading fixture onto awork site floor. Optionally, initiation may be associated with acombination of temporal characteristics of two or more sensor signals,or a combination of one or more temporal sensor signal profiles with oneor more instantaneous sensor signal values.

Optionally, the output signal from sensor 18 a or sensor 22 a may bedelivered to bus 14 as data for use by other initiators or by the firingcontrol system 12. The two-way communication between the firing controlsystem 12 and a specific initiator along bus 14 as described above mayinclude signals from a sensor specifically associated with a particularinitiator as sensor 22 a is specifically associated with initiator 22.The sensor signal, having been conveyed via bus 14, may optionally beread as input data by other initiators as well as by the firing controlsystem 12. The use of a sensor closely associated with an initiator asdescribed above results in improved reaction time for the initiator andthe system as a whole because the data required to determine whether theinitiator is ready to function is derived from a nearby source. Also,the size and weight of such sensors are smaller than that of sensors inprior art systems.

In one optional embodiment of the invention, any one or more ofinitiators 16, 18, etc., may be “self-arming”. Rather than dependingupon the receipt of an arming signal from firing control system 12, aself-arming initiator in accordance with the present invention mayrespond to signals received from internal or external sensors associatedtherewith, and/or signals received via bus 14 from firing control system12, one or more of sensor 18 a, sensor 22 a and sensor 24, etc., anddetermine whether such signals indicate a predetermined condition atwhich the initiator should arm itself. (Arming generally refers to thecharging of a firing capacitor whose subsequent discharge through thesemiconductor bridge will initiate the device). The energy for armingthe initiator may be supplied from a battery that serves only to arm theinitiators, or it may be drawn from firing control system 12, based onpower drawn from the power source for firing control system 12.Alternatively, the initiator control circuitry may arm the initiatorsolely in response to an arm command issued by the firing controlsystem. In another embodiment, the firing control system may be able toprovide power for arming the initiator directly, without having tocontrol the operation of an arming switch in the initiator.

It will be evident in view of the discussion above that an ordnancefiring system in accordance with the present invention that comprisesintelligent initiators differs from blasting-type initiation systemsbecause in a typical mining blast, the number and sequence ofinitiations is predetermined. The use of “intelligent initiators” thatrely on sensors as described herein to determine whether or not it isappropriate to arm and/or to fire the associated effector provides asystem in which an on-going assessment of the environment can determinewhich initiators function, even after the initial firing of the firstreactive effectors. In blasting operations, the arming decision is madeat a central control unit and once the blast has started, the systemgenerally does not provide any way for it to vary or alter in acontrolled, calculated manner the order or sequence in which detonatorsare fired.

In FIG. 1C, an ordnance firing system 310 in accordance with anotherembodiment of the invention is shown. System 310 comprises a firingcontrol circuit 312 which communicates with initiators 16, 18, 20 and 22via communication bus 14 in the same way that the firing and guidancecircuitry 12 (FIG. 1A) of rocket 10 communicates with correspondingstructures shown therein. In the embodiment of FIG. 1C, however, firingcontrol circuit 312 contains no power source of its own. Instead, itboth communicates and draws power from the guidance and controlcircuitry 313, which shares power from the low-energy power sourcetherein. Firing control circuit 312 is equipped with an input port 314for receiving communication signals and power from guidance and controlcircuit 313.

In an optional embodiment of an integrated ordnance system in accordancewith the present invention, the firing control system and at least oneinitiator are configured to provide a time-phased arming. In accordancewith this feature of the system, which will be described herein withreference to FIG. 2, a communication bus 14′ and firing control system(not shown) are configured to provide external arming power on one lineand an arm command communication signal on another line. The externalarming power is provided in order to arm initiator 16 a by chargingfiring capacitor 26 with energy sufficient to initiate the semiconductorbridge (not shown) in initiator 16 a. The external power must passthrough arming switch 28 to charge firing capacitor 26. Arming switch 28is designed to close only for a fraction of the time required to chargecapacitor 26 from bus 14′. Arming switch 28 is therefore referred to asa “momentary switch”. Arming switch 28 is under the control of armingswitch control circuit 30 which is part of the initiator controlcircuitry disposed within initiator 16 a. The arm command received viacommunication bus 14′ is conveyed to arming switch control circuit 30.In accordance with this aspect of the invention, arming switch control30 will only close arming switch 28 once for each arm command receivedso that firing capacitor 26 cannot progress from a fully dischargedcondition to a charge sufficient to initiate the semiconductor bridgeduring a single arming interval. Rather, each arming interval providesonly a partial charge for firing capacitor 26. Accordingly, a series ofarming signals is required, and a full charge can only be attained in astepwise fashion, as depicted in FIG. 3. Referring again to FIG. 2,firing capacitor 26 is connected in parallel with a bleed resistor 32which tends to bleed off the partial charges imposed on firing capacitor26. Accordingly, in order to fully charge firing capacitor 26, a seriesof arming intervals during which arming switch 28 is closed must occurwith sufficient duration and frequency to overcome the dissipativefunction of bleed resistor 32. The arming switch control circuit 30closes and opens arming switch 28 once and only once for each armcommand. Once armed, i.e., once firing capacitor 26 is chargedsufficiently to initiate the initiation element in the initiator, theperiodic arm commands must continue in order to maintain the sufficientcharge in capacitor 26. In effect, the configuration of circuit elementsshown in FIG. 2 provides a safety feature in which initiator 16 a canonly be armed for firing if arm commands are generated from the controlunit (not shown in FIG. 2) at a frequency determined by the requirementsof the circuitry in initiator 16 a. The specific requirements for arminginitiator 16 a make unintended arming and firing by virtue of strayelectromagnetic signals or as the result of malfunction of the controlunit highly unlikely.

FIG. 4 provides a schematic diagram of an initiator control circuit withseparate connection leads for input power and communication signals fromthe communication bus according to a particular embodiment of thisinvention. The conditioning circuit 34 of initiator 16 b converts theinput power to a direct current voltage that is suited for use by theremainder of the initiator circuitry. Optionally, conditioning circuit34 could have a high impedance to external potentials as an added safetyfeature against inadvertent initiation caused by stray signals or noiseas may be induced by ambient radio frequency signals. The input powerreceived by conditioning circuit 34 may be at various levels which maybe used as follows: at 0 to 5 volts, no significant reaction or responseis generated in initiator 16 b. A signal between 5 and 20 volts may beused for communication, to close switches for arming and firing, toobtain information in response to self-diagnostic sensors (not shown) ininitiator 16 b, etc., but signals at this voltage level are lower thanthe no-fire level of the initiator. This allows for communication withthe added safety feature of using signals which, even if misinterpretedas a firing signal, have insufficient magnitude to arm and fire thedevice. Signals at greater than 20 volts DC can be used forcommunication, to operate arming and firing switches, to obtain statusinformation and to fire the initiator. Voltage regulator 36 takes theconditioned input power and regulates it to a nominal voltage, typically3.3 or 5 volts DC for use by the processing/status circuit 38.

In the embodiment of FIG. 4, initiator 16 b preferably communicates witha firing control system (not shown) through a communication bus, througha hardwire link, inductive coupled link, a wireless link, an opticallink, etc. Alternatively, communication and power signals may bedelivered via a direct wire connection rather than over a bus.

The processing/status circuit 38 interprets commands sent from thefiring control system unit and performs the arming, firing, self-test,etc., functions and, when appropriate, issues a response signal to thefiring control system or, along a bus, to other initiators. Armingswitch 28 applies firing voltage to the firing circuitry 40. Initiatorfiring circuitry 40 will contain the necessary electronic, mechanical,optical, etc., components to force the initiator to function and willinclude, for example, a source of initiation energy such as a firingcapacitor (not shown), a firing switch (not shown), etc. The initiationelement 42 may be a semiconductor bridge or other low-energy, e.g.,planar, initiation element, or a prior art element such as a hotbridgewire, exploding bridgewire, etc.

There is shown in FIG. 5 an initiator 16 c in accordance with a specificembodiment of the present invention. Initiator 16 c is joined to a partyline bus 14. Signals received from the firing control system via bus 14pass through several buffer devices including common mode EMI(electro-magnetic interference) filter 44, high impedance isolators 46and over-voltage clamp 48. EMI filter 44 provides protection againstsusceptibility to random electromagnetic signals that may beinadvertently conveyed along bus 14. Impedance isolators 46 limit theenergy that can be received from bus 14 for use by the remainder of theinitiator circuit.

A signal that meets the requirements of the buffer provided by EMIfilter 44, isolators 46 and clamp 48 is then conveyed to arming switch28, power supply circuit 50 and data communication circuit 52. Aninitiator control circuit 54 receives input from data communicationcircuit 52 and power supply 50 as well as status information from energystorage (e.g., capacitor) 26 and the initiation element, e.g.,semiconductor bridge 42 a. When the proper input signals are receivedfrom these sources, initiator control circuit 54 may issue an armingsignal. In the illustrated embodiment, the arming signal is received bya logic gate 54 a which also receives input from an internal sensor 56.If the output of internal sensor 56 is appropriate for the operation ofarming switch 28, logic gate 54 a may convey the control arming signalfrom control circuit 54 to arming switch 28, through which a chargingvoltage may be applied to the energy storage device, i.e., a firingcapacitor 26. Optionally, charging may occur in a set fashion asdescribed in connection with FIGS. 2 and 3. When the initiating elementis a semiconductor bridge, the energy requirement for initiation issubstantially smaller than in prior art devices, so firing capacitor 26,which may typically be sized to release only 5 millijoules, may beemployed for a 1-ohm SCB, obviating the need for a battery as would berequired by prior art devices. When appropriate signals are received,control circuit 54 may issue a control firing signal for firing switch58. In the illustrated embodiment, an optional-logic gate 54 b comparesthe control firing signal to the output of an environmental sensor 18 aand only conveys the control firing signal to the firing switch when theenvironmental sensor 18 a indicates that conditions are appropriate forfiring. The closure of firing switch 58 permits the discharge of firingcapacitor 26 through the semiconductor bridge 42 a or other initiationelement, thus initiating the device.

In addition to providing input to logic gates 54 a and 54 b, internalsensor 56 and external sensor 18 a may provide signals directly toinitiator control circuit 54 and/or data communication circuit 52 sothat initiator 16 c can perform a self-test for readiness prior to thereceipt of an arming or firing signal from party line bus 14.Optionally, the self test can be performed in response to a query signalreceived from bus 14 and the results may be reported in a responsesignal emitted along bus 14.

As indicated above, the present invention also finds utility in landvehicles, e.g., in automobiles, trucks, buses, trains, etc., forpurposes that may include initiating the inflation of air bag safetysystems. In such applications, the ordnance firing system includessensors which signal to the firing control system circuitry the locationof an impact on the vehicle, the occurrence of a roll-over, or otherconditions that bear on which of the effectors, i.e., air bag inflators,should be initiated.

In the case of a land vehicle in which an ordnance firing system is usedfor initiating a safety system, e.g., air bag(s) and belt tensioners, acondition precedent to firing may be the sensing of an impact. Suchsafety systems are known and are disclosed in, e.g., U.S. Pat. No.5,829,841 and U.S. Pat. No. 5,829,784, both of which are incorporatedherein by reference as background information. The initial sensing of animpact may result in the issuance of a command to arm all the initiatorsin the system, but selected initiators might be programmed only to firewhen associated sensors indicate an impact in the area of the initiator.Thus, the ordnance system can be programmed only to inflate a driver'sside air bag when impact on the driver's side of vehicle is sensed. Incontrast, the ordnance system may be programmed to initiate othereffectors, e.g., seat belt tensioners, in response to a much broaderrange of sensor inputs, e.g., in response to the indication by anysensor of a vehicle impact. Thus, the ordnance firing system can beprogrammed so that some initiators are responsive to more sensor signalsthan others. In an alternative embodiment, certain sensor output signalsmay constitute conditions precedent to arming one or more of theinitiators and either the firing control system or the initiator controlcircuitry may be responsive to the sensor so that the initiator is notarmed until the sensor generates the appropriate signal.

The invention described herein provides initiators and an integratedordnance system in which the initiators may have a high input impedancewhich, in turn, provides simple EMI control, protection againstinadvertent initiation caused by transient signals and efficient energystorage. A variety of coupling arrangements may be used to establish alink between an initiator and a communication bus, including magneticcoupling. MEMS (micro-electronic machines) technology may optionally beincorporated for enhanced safety.

While the invention has been described in detail with respect toparticular embodiments thereof, it will be apparent that upon a readingand understanding of the foregoing, numerous alterations to thedescribed embodiments will occur to those skilled in the art and it isintended to include such alterations within the scope of the appendedclaims.

1-17. (canceled)
 18. In a land vehicle comprising a plurality ofreactive effectors, the improvement comprising: a plurality ofinitiators associated with the effectors; a firing control system incommunication with the initiators; and at least one sensor, on thedevice, for sensing a condition precedent to arming or firing at leastone initiator; wherein at least one initiator is in communication withthe sensor and that is responsive to the sensor and to the firingcircuitry for initiating its associated effector upon receipt of propersignals from both the firing circuitry and the sensor.
 19. The vehicleof claim 18 comprising a common bus through which the initiators arelinked to the firing circuitry.
 20. The vehicle of claim 18 wherein thesensor is connected to the bus.
 21. The vehicle of claim 18 wherein thesensor is connected to the initiator responsive to it.
 22. The vehicleof claim 18 wherein at least one initiator is programmed to self-arm orinitiate based on a signal received from the sensor.